Engine overheating? It is still starting to get hot after 10 minutes driving?

2004 BMW 330
250,000 MILES • 3.0L • 6 CYL • 2WD • AUTOMATIC
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SCC1981
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Hello 2CarPros,

I don't know what to do next.
My Car overheated and I changed the following:

Water pump
Thermostat
Fan
Expansion Tank
Cooler

It is still starting to get hot after 10 minutes driving. When it's cold I see it has lost a bit of coolant (maybe 50ml).
The heating does work (although there is something wrong with it: If i use "Auto" - the air flow is very low. If I do not use "Auto" it works fine.

What shall i do next to solve the problem?
Aug 15, 2022 at 3:40 AM
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STRAILER
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It sounds like the fan clutch is not working, do you hear the fan kick in when the engine is hot? If not, I would replace the fan clutch with a high-quality replacement. Here are the instructions on how to change the part out in the images below.

This guide may help as well:

https://www.2carpros.com/articles/engine-overheating-or-running-hot

Check out the diagrams (below). Please let us know what happens. Also check the front of the radiator to make sure a plastic bag is not stuck.
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Aug 15, 2022 at 10:47 AM
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SCC1981
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Hello Ken, the Fan has already been replaced....
Aug 15, 2022 at 10:49 AM
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SCC1981
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I put some coolant fix in yesterday. Today i checked again. The water pump is working (I see the water flow in the expansion tank). Both fans are working (Visco and electric). The car starts overheating still. Today even before the heating started to work. I am desperate....
Aug 16, 2022 at 3:09 AM
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STRAILER
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It sounds like the radiator is plugged either internally or externally (dirt) check out the guide in the above post, also we should check for a blown head gasket. This guide will help with that, and I have included how to change the radiator in the diagrams below:

https://www.2carpros.com/articles/head-gasket-blown-test

Check out the diagrams (below). Please let us know what happens.


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Aug 17, 2022 at 11:08 AM
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SCC1981
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Hi Ken, I will clean the cooling system and will do a head gasket test. I will report again...

Best,
Chris
Aug 17, 2022 at 1:05 PM
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STRAILER
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Sounds good, let me know how it turns out please.
Aug 18, 2022 at 2:09 PM
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SCC1981
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Hey guys,

so today i tried the LIQUI MOLY Radiator Cleaner. It did something positive to the car as the heating is working fine again. However, after 20 minutes the car started overheating again and the thermostat didn't open (the lower radiator hose was still cold). I wonder if the thermostat can be blocked somehow....
It's a new thermostat and i really doubt it can be broken as the lower radiator hose got hot last time - shall i remove the hoses and try to clean the thermostat?
Best,
Chris
Aug 19, 2022 at 9:09 AM
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STRAILER
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It sounds like you may have a defective thermostat.
Aug 19, 2022 at 11:41 AM
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SCC1981
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Is it possible that a new thermostat works for a few days and then stops working?
Aug 19, 2022 at 12:21 PM
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STRAILER
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Yes, that is possible. Also, I have heard of people raising the front and rear of the car to help get air bubbles out of the system.
Aug 20, 2022 at 4:24 PM